For many kinds of adverb, there is some latitude in where an adverb appears in a sentence. Generally, for adverbs of place, the adverb goes either after the verb, or at the end of the clause that it modifies. In this case, the verb is celebrating, and the clause is "people are celebrating", so both standard options produce the same sentence:
People are celebrating everywhere the landing of the Apollo 11 mission.
This sentence just doesn't sound right: but the problem is even bigger when we try to use similar adverbs of place:
People don't like here dogs
People don't like dogs here
The first one is definitely wrong, and the second just doesn't convey the same meaning as
People here don't like dogs
I think that we can explain this by saying that, although the dictionary says it's an adverb, we are thinking of its meaning as the prepositional phrase in this place, which can modify either a verb or a noun. What we want to say is
People in this place don't like dogs
Words like here, there and everywhere can be used to modify nouns and verbs. Their role as adverbs (modifying a verb) is undisputed, but their ability to modify nouns is not easy to explain. They are not adjectives, because they are placed after the noun that they modify, not before. Their role cannot therefore be defined by conventional grammatical terms, and is equivalent to that of a prepositional phrase.
